Posted By el Toro Posted On

What is the reason behind the black smoke generated by warships?

At present, many people misunderstand the phenomenon of black smoke coming from warships, thinking that it is a manifestation of old and outdated technology. Actually, when a warship with full power is normally started, there is often a small amount of black smoke coming out. Other reasons due to which the black smokes generates are related with power, or the use of fuel, specifically the warships which uses diesel or oil boiler power systems, black smoke occurs in them because of the type of fuel used in them.

Specifically, one of them is a dynamic factor. Generally speaking, warships generally choose engines suitable for their own characteristics in various methods such as diesel, steam and gas. For all-electric propulsion warships, they are also inseparable from the above-mentioned means for power generation operations. These diesel engines and other power plants need to be propelled by more cost-effective heavy oil, which is a special feedstock that is significantly different from light oil.

Black smoke is not the patent of old warships, what is the reason?A brief  analysis is as follows - iMedia

The so-called heavy oil is the residue from the normal extraction of crude oil, which is mainly composed of hydrocarbons, but also includes other substances such as sulfur. In terms of characteristics, this raw material has the properties of high viscosity, macromolecules and low purity. Due to the inability to fully burn, the black smoke phenomenon is derived from those warships that use heavy oil.

From the above statement, the power system of the warship and the fuel used are main reasons for the black smoke. Specifically for destroyers and frigates, they are equipped with diesel engines or diesel-fuel combined power systems in pursuit of high speed. Among them, the former has the advantage of low fuel consumption, even lower than that of gas turbine and boiler steam turbine.
USS Iowa (BB-61) firing a full broadside during firepower demonstrations on  August 15, 1984. [2354x3000] : r/WarshipPorn

At present, the existing destroyers and frigates in the world are generally equipped with diesel engines or diesel-fuel combined power systems. Of course, the disadvantages of diesel engines are also obvious. Those warships with high-power diesel engines are more concerned with cost-effective factors. But no matter whether the warship uses diesel engines, as long as heavy fuel oil is used, black smoke will appear during the start-up process, which is inevitable.

However, it is worth noting that if the destroyers and frigates are powered by gas, the black smoke phenomenon will be completely gone. It’s not that the military is reluctant to use heavy oil, but because gas power cannot accommodate the fuel of heavy oil!

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In addition, aging of the warship body and imperfect post-maintenance are also causes of black smoke, as this prevents the heavy oil from being effectively atomized and causes insufficient combustion.